/**
  * This method updates the account balance.
  *
  * @param accountId The id of the account which needs to be updated.
  * @param amount The amount by which the account needs to be updated.
  */
 private void updateAccountTotal(Long accountId, Double amount) {
   if (amount != null && amount != 0) {
     Account account = accountRepository.findOne(accountId);
     account.setBalance(account.getBalance() + amount);
     accountRepository.save(account);
   }
 }
 /**
  * This method gets the balance for the given account.
  *
  * @param accountId The required account id.
  * @return The balance of the given account.
  */
 private Double getCurrentAccountBalance(Long accountId) {
   return accountRepository.findOne(accountId).getBalance();
 }